On 11/4/19 9:18 AM, Christian Borntraeger wrote:
>
>
> On 24.10.19 13:40, Janosch Frank wrote:
>> Let's add a KVM interface to create and destroy protected VMs.
>>
>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
>> ---
>> arch/s390/include/asm/kvm_host.h | 24 +++-
>> arch/s390/include/asm/uv.h | 110 ++++++++++++++
>> arch/s390/kvm/Makefile | 2 +-
>> arch/s390/kvm/kvm-s390.c | 173 +++++++++++++++++++++-
>> arch/s390/kvm/kvm-s390.h | 47 ++++++
>> arch/s390/kvm/pv.c | 237 +++++++++++++++++++++++++++++++
>> include/uapi/linux/kvm.h | 33 +++++
>> 7 files changed, 622 insertions(+), 4 deletions(-)
>> create mode 100644 arch/s390/kvm/pv.c
> [...]
>
>> + case KVM_PV_VM_UNPACK: {
>> + struct kvm_s390_pv_unp unp = {};
>> +
>> + r = -EFAULT;
>> + if (copy_from_user(&unp, argp, sizeof(unp)))
>> + break;
>> +
>> + r = kvm_s390_pv_unpack(kvm, unp.addr, unp.size, unp.tweak);
>> + break;
>> + }
>
>
>
> [....]
>
>> +int kvm_s390_pv_unpack(struct kvm *kvm, unsigned long addr, unsigned long size,
>> + unsigned long tweak)
>> +{
>> + int i, rc = 0;
>> + struct uv_cb_unp uvcb = {
>> + .header.cmd = UVC_CMD_UNPACK_IMG,
>> + .header.len = sizeof(uvcb),
>> + .guest_handle = kvm_s390_pv_handle(kvm),
>> + .tweak[0] = tweak
>> + };
>> +
>> + if (addr & ~PAGE_MASK || size & ~PAGE_MASK)
>> + return -EINVAL;
>> +
>> +
>> + VM_EVENT(kvm, 3, "PROTVIRT VM UNPACK: start addr %lx size %lx",
>> + addr, size);
>
> Does it make sense to check for addr and addr+size to be within the memory
> size of the guest? The uv_call or gmap_fault will fail later on, but we
> could do an early exit if the the site is wrong.
Yeah, Marc already brought that up because of a testcase of his.
I'll add a check, but before that I need to understand what makes us
loop so long that we get RCU warnings.
>
>
>
>
>> + for (i = 0; i < size / PAGE_SIZE; i++) {
>> + uvcb.gaddr = addr + i * PAGE_SIZE;
>> + uvcb.tweak[1] = i * PAGE_SIZE;
>
>
>> +retry:
>
>> + rc = uv_call(0, (u64)&uvcb);
>> + if (!rc)
>> + continue;
>> + /* If not yet mapped fault and retry */
>> + if (uvcb.header.rc == 0x10a) {
>> + rc = gmap_fault(kvm->arch.gmap, uvcb.gaddr,
>> + FAULT_FLAG_WRITE);
>> + if (rc)
>> + return rc;
>> + goto retry;
>> + }
>> + VM_EVENT(kvm, 3, "PROTVIRT VM UNPACK: failed addr %llx rc %x rrc %x",
>> + uvcb.gaddr, uvcb.header.rc, uvcb.header.rrc);
>> + break;
>> + }
> [...]
>
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